Machine for grinding and sharpening broaches



April 5, 1938.

W. G. BALDENHOFER MACHINE FOR GRINDING AND SHARPENING BROACHES Filed June 14, 1957 15 Sheets-Sheet l Jmqe tor (Ittornega April 1938. w. e. BALDENHOFER 2,113,287

MACHINE FOR GRINDING ANDISHARFENING BROACHES Filed June 14, 1937 15 Sheets-Sheet 2 7 ttorneg S April 5, 1938. w. cs. BALDENHOFER 2,113,287

MACHINE FOR GRINDING AND SHARPENING BROACHES Filed June 14, 1937' 15 Sheets-Sheet s attorneys April 5,1938.

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MACHINE FOR GRINDlNG AND SHARPENI NG BROACHES Filed June 14, 1937 15 Sheets-Sheet 5 8g I m m ,1, I Cfltornegs April 5, 1938. w. GQBALDENHOFER MACHINE FOR GRINDING AND SHARPENING BROA CHES Filed June 14, 1957 Ill m- IYL r m M m e o m m 63 fi 2 e v m. 0 HI m m lb n H 9 .1 :J 4 n I n! 8 0O 5 law/ w 5% m I 0 l April 1933? G. BALDENII-IOFER 2,113,287

MACHINE FOR GRINDING AND SHARPENING BROACHES Filed June 14, 1937 15 Sheets-$11691; 7

- Snventor r I I attorneys April 5, 1938. w. G. BALDENHOFER MACHINE FOR GRINDING AND SHARPENING BROACHES 15 sheets-sheet 9 Filed Junev 14, 1937 April 3 w. e. BALDENHOFER Q 2,113,287

MACHINE FOR GRINDING AND SHARPENING BRO'ACHES Filed .June 14, 1937 15 Sheets-Shef l0 3 nventor 07W x& arc 4% will (Ittorngs April 5, 1938.. w. e, BALDENHOFER 2,113,237,

V MACHINE FOR GRINDING AND SHARPENING BROACHES Filed June 14, 1937 15 Sheets-Sheet 11 N w l H. 3

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MACHINE FOR GRINDING AND SHARPENING BRO-\GHES l5 Sheets-Sheet 12 Filed June 14, 1957 (Ittqmeg 4 April 5, 1938.

MACHINE 'w. e. BALDENHOFER 2,113,287 FOR GRINDING AND SHARPENING BROACHE'S Filed June 1937 l5. Sheets-Sheet l3 N Imoentor 07M )6: m1

Clttornego April 5, 1938.

w. G. BALDENHOFER 2,113,287 MACHINE FOR GRINDING AND SHARPENING BROACHES Filed June 14, 1937 15 Sheets-Sheet '14 ento \ GttornegS 15 'Sh eets She et 15 Summer attorneys w. G. BALDENHOFER MACHINE FOR GRINDING ANJ JISHARFE NING BROACHES Filed Jun 14, 1957 April 5,- i938;

Patented Apr. 5, 1938 UNITED STATES PATENT OFFICE William G. Baldenhofer, Springfield, Ohio, as-

signor to The Thompson Grinder Company, Springfield, Ohio, a corporation of Ohio Application June 14, 1937, SerialNo.148,081 25 Claims. (01.51-56) This invention relates to improvements in machines for grindingand sharpening broaches, it more particularly relating to machines which are adapted to perform this work automatically.

While broaches have been in use for many years, it has only been recently that an extensive use has been made of them, more particularly in the automotive and refrigerator manufacturing fields, and breaching machines at times having.

several broaches are now employed in great numbers. Generally, there are more flat broaches than any other kind, such broaches being used to machine pads, bosses and the like on work pieces held in fixtures, and the machine here illustrated and described is more particularly adapted to the sharpening of flat'broaches, although some of its principles are equally applicable to the sharpening of round broaches. The broaches are removably secured to the breaching machines so that they may be taken off and re-sharpened, which operation is necessary in some cases every two or'three days.

The machine consists broadly of the following parts: A support is provided for the broach during the sharpening operation which in the present case is a magnetic chuck mounted on a table together with means for imparting a step-by-step feeding 'inovement'to the table, the chuck being mounted on the table at a predetermined angle cation of the grinding wheel is accurately timed with the step-by-step feeding movement of the table that supports the broach so that when the grinding wheel is withdrawn from its grinding position with relation to the broach the table will be fed to bring the next tooth in line with the grinding wheel which is then given another cycle of movement and so on until the forward working faces of the teeth of the broach have all been operated upon.

The table" which supports the broach is restored to. its initial starting position, another grinding wheel of a cup-type is substituted for the disk type grinding wheel andthe operation repeated to grind the lands of the teeth of the broach.

The step-by-step movement of the table which supports the broach is accomplished by a hydraulic motor, the control valve of which is acthe broach that it \will act to stop the feed of tuated by electrical means set in operation by an electrical switch whose actuating devices are located in the path of the broach teeth so that when any one of the teeth makes contact therewith it will stop the feedingmovement of the table and set in operation another hydraulic motor by controlling its valve to impart reciprocation to the grinding wheel head, the grinding wheel head .making one cycle of movement and stopping by a form of hydraulic and electrical control.

The control member which makes contact with the teeth of a broach is mounted upon the tool head and is brought out of engagement with the teeth as the too] head moves to bring the grinding wheel into operative'position with the teeth. As the tool head completes its cycle of movement controlling devices connected therewith operate to stop the'hydraulic motor which moves the tool head and start the hydraulic motor that moves the table The tooth that is to be ground is the one that is contacted by the table stopping mechanism. Therefore, this machine is adapted for the grinding of broach teeth which are either regularly spaced or irregularly spaced which would relieve the manufacturer of making broaches with regularly spaced teeth for convenience in sharpening.

One of the objects of the invention is the provision of a grinding machine for sharpening'go' broaches whereby the initial sharpening operation of the cutting edges of the broach teeth may be carried out automatically, and by the same operation a re-sharpening operation may be performed upon the teeth of thebroach which have become dulled from use.

A further object of the invention is to provide'in a machine of this character in which the broach' to be sharpened or given a step-by-step feeding movement, automatic means controlled by the broach teeth for stopping the feedingmovement of the broach at a proper point to be operated upon by a reciprocatory grinding wheel; a further and more specific object in this connection being to provide an operating member adapted to be brought alternately in the path of the forward or cutting sides of the broach teeth, which member is so connected with the control device of the step-by-step feeding mechanism for the broach when it is contacted by a tooth.

A further object of the invention is to provide in a machine of this character which has a reciprocatory grinding wheel, automatic means for imparting a reciprocatory movement to the grinding wheel at each stoppage of the broach feeding mechanism and thereafterarresting the reciprocatory movement of the grinding wheel until a succeeding broach tooth has been fed and stopped in cooperative relation with said grinding wheel.

A further object of the invention is to provide simple and effective means for adjusting the angle of the grinding wheel to bring it into conformity with the angle of the broach teeth.

A further object of the invention is to compensate for the taper of the breach to be sharpened by providing simple and effective means for elevating the low end of the breach to bring all of the teeth of the breach in the same relation with the grinding wheel.

In the accompanying drawings:

Fig. 1 is a, front elevation of the broach grinding machine.

Fig. 2 is a fragmentary view partly in side elevation and partly in vertical section on a slightly enlarged scale of a portion of the machine as shown in Fig. 1.

Fig. 3 is a fragmentary horizontal section on the line 33 of Fig. 2.

Fig. 4 is a fragmentary top plan view of the machine on the same scale as Fig. 1.

Fig. 5 is an enlarged fragmentary front elevation of the machine showing an arrangement of the grinding wheel and electric control devices for one grinding operation.

Fig. 6 is a view similar to Fig. 5 with the parts therein shown in position for another grinding operation.

Fig. '1 is a side elevation of the machine on a slightly enlarged scale as compared to Fig. 1.

Fig. 8 is a fragmentary horizontal section on the line 8-8 of Fig. 7.

Fig. 9 is a fragmentary side elevation of a portion of the machine on a larger scale, it being a view of a portion of the grinding wheel motor carrying devices.

Fig. 10 is a view similar to Fig. 9 partly in elevation and partly in section, the portion in section being taken on the line lI-IO of Fig. 1.

Fig. 11 is a partial transverse vertical section on a larger scale on the line ll-|l of Fig. 10.

Fig. 12 is a fragmentary longitudinal vertical section on a reduced scale on the line I2-I2 of Fig. 11.

Fig. 13 is a horizontal sectional view on the line l3l3 of Fig. 9 withportions broken away position.

I draulic controlling device.

Fig. 15 is a fragmentary view similar to Figs. 13 and 14, but with certain of the parts in a still different working'position as compared to Fig. 14.

Fig. 16 is a perspective view on a larger scale supplementing Figs. 13, 14, and 15 of portions of thewheel head controlling devices in one working position with portions being shown partly in section. I

Fig. 17 is a view similarto Fig. 16 but with the parts in a different working position Fig. 18 is a view similar to Figs. 16 and 17 with the parts in a still different working position.

Fig. 19 is an elevation of a wheel head hy- Fig. 20 is a' transverse section on the line 20-20 of Fig. 19. 7} Fig. 21 is a view similar to Fig. 20 with one'of the parts in a different working position.

Fig. 22 is a view partly in elevation and partly in section on a larger scale as compared to Figs. 7 and 9 of a deviceemployed in controlling movements of the work piece supporting means, i. e., an electric switch.

Fig. 23 is a fragmentary section on the line 23-23 of Fig. 22 showing the switch in end elevation. i

Fig. 24 is a horizontal fragmentary section on the line 24-44 of Fig. 23 showing a. top plan view of the switch.

Fig. 25 is an elevation of a portion of the switch devices shown in Fig; 22 with some of the parts in a different working position.

Fig. 26 is a view similar to Fig. 25 showing the same parts in an ensuing working position.

Fig. 27 is a view similar to Figs. 25 and 26 but with the parts in a still different working position.

Fig. 28 is a front elevation of an electrical de-' vice and a portion of its supporting means. the

' ing switch.

Fig. 29 is a side elevation of the switch.

Fig. 30 is anenlarged front elevation with a small portion in section of the switch with the front cover removed.

Fig. 31 is a view partly in elevation and-partly in vertical section of the device shown in Fig. 30, the sectional portion being taken on the line 3 l-Sl of Fig. 30, the view showing the cover in place.

Fig. 32 is a fragmentary side elevation of the lower portion of the device shown in Fig. 30.

Fig. 33 is an enlarged fragmentary front elevation of some of the devices shown in Fig. 1

with the control panel removed and portions ofin'place; a portion of the view is in longitudinal section.

Fig. 36 is a view partly in elevation similar to Figs. 33 and and on the same scale, and partly in longitudinal vertical section, the sectional portion being taken on the line 3648 of Fig.- 34. The view shows parts in a different working position.

Fig. 3'? is a fragmentary transverse vertical section on the line 31-41 of Fig. 34.

Fig. 38 is a fragmentary horizontal section on the line 38-30 of Hg. 37. Fig. 39 is a schematic illustration of the hydraulic control system, a portion of the diagram'being in perspective.

, Fig. 40 is a diagram of the electrical control ling circuits. I

Fig. 41 is a. fragmentary top plan view of a detail, 1. e., a work-piece supporting device in the form of a typical magnetic chuck having my improved-devices for tilting the chuck to a desired angle. I

Fig. 42 is a front elevation of the chuck and tilting fixtures illustrated in Fig. 41.

Fig. 43 is a view similarto Fig. 42 but showing the chuck in a different working position.

Fig. 44 is an and elevation of the left end ofthe chuck and fixture.

"Fig. 45 is an end elevation of the right end of with broken-away portions shown in longitudinal section. a s

Fig. 47 is a fragmentary view similar to the left end of Fig. 43 but on the increased scale of Fig. 46 with broken-away portions shown in longitudinal section. The view shows the device in a different working position.

Fig. 48 is a fragmentary partial top plan and horizontal sectional view of the left end of the chuck and fixture, the sectional portion of the view being taken on the line 4848 of Fig. 46.

' Fig. 49 is an enlarged fragmentary front elevation of the chuck tilting fixture, showing the graduated collars.

Fig. 50 is a plan view of a typical fiat broach.

Fig. 51 is a side elevation of the same broach as seen in Fig. 50, showing in an exaggerated manner the taper of the broach.

Fig. 52 1s a plan view of a typical fiat broach having cutting teeth disposed angularly to provide a shearing cut.

Fig. 53 is a plan view of a typical broach similar to the broach seen in Fig. 52, except that the angularly disposed teeth are of opposite hand.

Description of typical flat broaches Referring to the drawings and especially to Figs. 50 to 53, inclusive, typical fiat broaches are shown, hereinafter referred to as the work-piece or work. The improved grinding machine of the present application has been designed for the grinding of such broaches in an accurate and convenient manner. Reference is made not only to grinding operations on the teeth involved in the manufacture of new broaches, but also to the sharpening operations on broaches which have become dull in service.

To a certain extent, a flat broach may be likened to a large file, by the use of which in the especially designed broaching machines now employed, a surface such as a boss or face of a pad on a casting, forging or like work-piece secured to the forward side of the ram of a broaching machine, which ram generally is adapted to slide vertically in vertical ways in the broaching machine, a descent from the upper portion and return thereto, being termed the working and return strokes, respectively, of the ram and broach.

Referring to Fig. 50, it will be seen that in the forward side of the flat broach 25 there is formed a series of teeth 24 and in the descent or working stroke of the ram, each successive tooth of the broach engages a casting or forging or the like held in a suitable fixture and removes stock from the same and thereby finishes the surface.

Although the procedure following varies in,

practice, the casting may beremoved at this time, the operator then returning the ram and broach to the upper portion of the ramways in readiness for a following working stroke.

- In some instances, the cutting teeth are formed in the broach substantially squarely across the face of the broach, as indicated in Fig. 50. While this formation may serve for some metals, it is more often found that the teeth are formed angularly across the broaches 26 and 21, as seen in Figs. 52 and 53, whereby a shearing action is provided. These views show instances of varying tooth angles 28 and 28, and also how the inclination of the teeth of one broach may be opposite to that of the inclination of another, for the purpose of neutralizing the side-thrust developed by any of a plurality of broaches employed in a multi-broach machine.

Heretofore, the manufacture and sharpening of the teeth of flat broaches has been performed on a variety of grinding machines, substantially all of which are improvised machines and manually operable. Movements by hand of certain elements of the early grinding machines such as the work table, toolhead, etc, may be but slightly slower per movement than is found for corresponding elements in the machine of the present application, when such hand is operated by an experienced operator, yet the experienced operator has difficulty in rapidly and correctly spotting the table for the action of the grinding wheel on a particular broach tooth.

It will be explained that by the present electrohydraulic control system, each tooth is spotted more readily than by any hand method, and, further, the uniformly smooth movement imparted to a tool-head by the hydraulic system employed is such than wheel wear is reduced. If wheel wear is excessive in the length of a broach, it may not be possible to provide that the tooth increments of the teeth last ground are as intended, such teeth possibly taking heavier cuts than are contemplated, with the result that tooth breakage occurs, or at the best, the finish of the surface so far as quality is concerned is poorer.

Also, in some of the earlier grinding machines,

the capacity of the machine as regards broaches having a shearing cut tooth angle is limited to broaches of comparatively small angle. To grind one having a comparatively large angle, it is often necessary to reset the broach one or more times, with resulting slight errors that affect accuracy and quality of finish obtained.

General description of machine Referring to the drawings, l represents a base on which is slidably mounted a table 2 in a V- way 3 and a flatway 4. On the upper surface of the table is mounted a magnetic chuck 5 with arrangement for tilting by raising one end higher than the other by means of fixtures which will be described later. The grinding wheel 6 is driven by a small motor 6' which is swivelly mounted by means of a dowel in a slide 8. The slide 8 is arranged for movement by a screw 8' and hand wheel 8" thereon in a horizontal direction by a dovetailed slide arrangement (Figs. 2 and 3) in the lower downturned leg9 of an angular toolhead bracket Ill which in turn is slidably supported on the lower side 'of a swivel casting mem- I ber H. In the present instance the mounting of the tool head bracket ID for slidable motion with reference to the swivel casting II is by means of ball bearings, there being a series of balls l2 on each side (Fig. 11), a central stationary ball race member l3 having a V-groove raceway I4 in each side attached to the lower portion of the swivel member II. In the upper horizontal portion of the tool head bracket I0 companion raceways l5 are secured, one on each side, the one on the right in Fig. 1 and Fig. 11 being clamped by a retaining bar l6 while the raceway from the left side is clamped by a retaining bar I! with a taper gib I8 being interposed between the vertical side IQ of .the angle bracket III in order to provide an adjustment of the pressure of the raceway on the balls to take up for wear. I g A The swivel member II is swivelly supported on the under side of the projecting portion 20 of the saddle member 2! by means of T-head bolts 22 whose heads are let into a circular T-slot 23. A hollow boss ll (Fig. 10) on the upper side of the swivel member fits into a bore H" in the lower portion of the projecting portion 20, the T-slot 23 being concentrically disposed with relation to the axis of the boss I l. The boss II is preferably of the comparatively large size shown in order to provide that the electrical conductors, conduits and the like essential to the operation 82 the tool head may pass through this hollow It is thus seen that the swivel member may be swung from the right or left to the tooth angle as found on the broach to be ground. For example, the tooth angle 28 on the broach 26, Fig. 52, indicates that the swivel II should be set to a corresponding angle as shown by the full line position of the member I l in Fig. 4. A protractor scale 29 is provided to enable the operator to conveniently arrive at the proper setting. Also, for broaches having teeth of the angle 28' as shown for the'broach 21 (Fig. 53) or of the opposite inclination, the swivel member l is set to the broken line position in Fig. 4. The swivel member is set at right angles to the length of the broach 25 as seen in Figs. 1 and 7.

Tool head elevating and lowering means In order to adjust the grinding wheel 6 to broaches of difierent thicknesses the saddle 2| carrying the grinding wheel and motor is slidably mounted on column ways 30 on a column 3|, gib angle members 32 (Fig. 4) being employed to secure the saddle to the column ways and tapered gibs 33 being further provided to make. the necessary adjustment to take up wear. The column II is secured in any suitable manner to a projection 34 of the base I, Figs. 4 and 7.

The saddle 2| is elevated or lowered by means of an elevating screw 35 suspended at its upper end on a double-row anti-friction bearing 36 (Fig. 7) and radially supported at its lower end on an anti-friction bearing 31 secured in the free end of a bar 38 (Fig. 8) attached to the base I. Attached to the rear side of the saddle 2| is a nut 33 in which the elevating screw is threaded and to provide transmission of motion from the elevating hand wheel 40, Figs. 1, 4, and 7, a train of gears is employed consisting of a gear 4| pinned to the lower end of the elevating screw 35 and a similar gear 42 (Fig. 8) pinned to the upper end of a short shaft 43 journaled in the base, an idler pinion 44 journaled on a vertical stud 44' being interposed between the gears 4| and 42. On the lower end of the short vertical; shaft 43 is a beveled gear 45 (Fig. 7) with which meshes a bevel pinion 46 on the inner end of a horizontally disposed shaft 41 extending through the front of the base and having attached at its forward end the elevating hand wheel 40 previously referred to.

By this means and with the right-hand thread of the elevating screw 35, rotation of the hand wheel in an anti-clockwise direction lowers the saddle 2| and with it the grinding wheel, while rotation in the opposite direction or clockwise elevates the saddle. It will be noticed from Fig. 7 that the projecting portion 20 of the saddle 2| overhangs the work table 2 and the chuck 5 and broach mounted thereon and. that the disposition of the swivel casting member I I is such as to pro- -vide fore and aft movement of the wheel over the work.

Hydraulic system The power for manipulating the work table 2 andthe grinding wheel head is by hydraulic motors electrically controlled. Referring to the means employed for providing motion to the work 'table there is provided a hydraulic motor indicated in general at 48 consisting of a cylinder 49 (Fig. 1) having a cylinder head 50 secured to the base I, and a cylinder head 5| at the right end of the cylinder through which passes a cylinder piston rod 52. Within the cylinder 49 is slidably disposed a piston 53 on the inner end of the piston rod 52 while the outer end of the piston rod 52 is secured to a bracket 54 attached to the apron 55 of the work table 2.

The tool head receives its motion for traversing the work piece by means of a hydraulic motor secured by screws or otherwise to the upper surface of the wheel head bracket Hi, this bracket passing through an elongated slot 62 (Figs. 13, 14, and 15) in the bottom horizontal portion 63 of the swivel member ll.

The hydraulic fluid supplying motion to each of 'these pistons is provided by a hydraulic system shown in Fig. 39, which figure shows the piping diagram of the entire hydraulic system. A suitable pump shown conventionally at 64 may be driven by any means such as the electric motor 55. To thesuction side of the pump 64 is connected the suction conduit 66, the lower end of which extends into the tank 61 housed in the hollow interior of the base I. From the discharge side of the pump 64 a conduit 68 leads to the first of a pair of pressure regulator valves, it

pressure supplied by the pump and the pressure supplied to the work table master valve II is discharged through a short conduit 12 to the second of the pressure regulator valves 13 which regulates the pressure flowing to tool head throttle valve 14 through the conduit I5 and from this tool head throttle valve 14 directly to the tool head cylinder 56. The pressure supplied by the second regulator valve 13 may. preferably be in the neighborhood of 40 pounds per square inch and the surplus fluid is discharged again to the tank by means of a conduit 16.

Fluid is supplied to each end of the table hydraulic motor 48 by conduits, there being a conduit TI connecting the left side of the work table master valve body H with the right end of the table cylinder 49 and a conduit [8 connecting the right end of the master valve body II with the left end of the table cylinder 49. A more detailed description of the work table master valve body follows: Referring to Figs. 33 to 37, inclusive, there is shown the work table valve body II previously referred to which is located horizontally within the interior of the base I, there being a large opening I in the forward wall of the base to provide access to the valve body II. Slidably disposed for reciprocating movements is the table control piston valve 19. This control valve I9 may be manually reciprocated or as will be described, by electrical means, in the presport BI is proportioned to the breadth of the central spool 19' so that when the control valve I9 is at neutral position as shown in Fig. 35 admission of fluid is stopped by the central spool.

In communication with the horizontal bore in which the control valve 19 reciprocates is a pair of ports, one of which on the left and indicated at 82 communicates with the conduit 11,

while the other 83 on'the right hand side communicates with the conduit I8, the conduit 11 leading to the right end of the table cylinder 48 and the conduit I8 leading to the left end of the table cylinder 48.- At 84 and 85 respectively on the left and right of the control valve body II are exhaust ports leading to a common exhaust cavity 86 horizontally disposed in the rear portion of the control valve body II, Fig. 38, from which leads a conduit 81 directly to a throttle valve 88 whereby the work table is controlled, both as to starting, stopping and speed thereof. The reason for placing the work table throttle valve 88 in the exhaust line will be explained later. All exhaust fluid passing through the throttle valve 88 is conducted by a conduit 89 preferably through an oil purifier 90 (Fig. 30) of any suitable type and from the oil purifier through a conduit 9| returning to discharge into the tank 6'! through the foot valve 92, by means of which a slight back pressure of say 4 pounds to the square inch is built up in the conduit 9|. This is done in order to provide lubrication for the work table ways 3 and 4, and also to prevent undesired drainage of fluid .from the cylinder and connected piping. The conduit 9| is branched at the point 94 to provide the conduit 95 leading to the table ways, a valve 93 being interpose d therein to control passage of the fluid to the ways. a

Manual control of .table movement To provide for manual control of the table, the main control valve 19 is actuated mechanically by a hand lever 96 positioned in a generally horizontal location on the forward side of the base I. The lever 96 is secured by pinning or other means to the forward end of a short cam shaft 91 (Fig. 34) horizontally disposed and journaled in a bracket 98 secured to the forward side of the base, the cam shaft passing interiorly through an opening in the base. 1

On the inner end of the cam shaft 91 is secured a cam 99 substantially in line with the table control valve I9. The lever 96 may be placed in any one of three positions and is preferably locked by the insertion of a springpressed plunger I into any one of three arouately disposed openings (Fig. 35) in the panel IOI which covers and protects the valve arrangement. When placed in the central opening IOI the effect is to cause the control valve 19 to assume the central or neutral position, in which' position the table will not move. By moving the lever. 96 upwardly to the full line position, Fig. 36, the plunger I00 entering the upper opening |0I", the table will move to the right by hydraulic power. By placing the lever 96 downwardly to the dot-dash line position, the plunger I00 entering the opening IOI, the table will move to the left, also by hydraulic power.

To obtain these movements, the cam is connected mechanically with the control valve I9 through the medium of-the armature I02 of a solenoid arrangement I18 to be described more fully in connection with the explanation of the electrical control circuit. For the present, it is stated that for convenience, this particular sole-- noid I18 is secured to the left-hand end of the valve body II whereby the solenoid armature may be directly connected to the extension 80' of the control, valve I9, and it is therefore convenient to actuate the valvel9through the connection of the cam 99 with the armature.

The camming surfaces by which these movements are produced are milled in the flat extending portion of the cam so" as to provide that the camming surfaces are substantially tangentially straddling the cam 99. Secured in the left-hand end of the straps I03 and passing through the opening in the cam whose outlines form the camming surfaces is a pin I04.

As can be seen from Fig. 36 if the control lever whereby fluid under pressure will be admitted from the port 8| through the valve bore and into ,the port 83 to the left end of the table hydraulic motor 48 to move the table to the right by hydraulic power. Also, if the control lever 96 is moved downwardly tothe dot-dash position, Fig. 36, the cam surface indicated at I08 in the control cam 99 will move the valve and solenoid arrangement to the extreme right end of the valve travel as indicated by dot-dash lines. During the time the table moves to the right, the exhaust fluid flowing from the right-hand end of the table hydraulic motor 48 flows through the conduit 11, port 82 and through the valve bore to the exhaust port 84 to the common exhaust port 86. When the table control lever 96 has moved the valve to the dot-dash line to produce table movement to the left, the left end ofthe table hydraulic motor is in communicationwith the exhaust conduit through the port 83 and through the valve bore to the exhaust port 85, and thence to the common exhaust port 86.

Between these extremes of movement as produced by the cam in manual operation and whereby the table may be-moved from right to left, or left to right, at any speed desired under thecontrol of the table throttle valve I4, there is a mid point associated with a central positioning of the lever 96. When the control lever 96 is placed in this central position as shown in Figs. 33, 34,

96 is moved to the full line position that portion 

